Aiha has been Bishamon's Shinki for 50 years. She used to be Bishamon's primary godly clothing, however was recently replaced by Tsuguha due to Bishamon tripping on Aiha's skirt too much. Aiha accompanied Bishamon as her suit of armor when Bishamon went to Yomi to bring back Yato. However, she suffered damage to her legs in that battle and was wheelchair-bound for quite some time afterwards.

(Source: Noragami Wikia)